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Yucca Mountain Will Be The Most Radioactive Place On Earth

Munkey

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Nuclear waste is hot, physically and politically. And there is no place where you can feel the heat more than at Yucca Mountain, Nev. The federal government is preparing to make this hauntingly beautiful patch of desert 100 miles northwest of Las Vegas the most radioactive place on Earth. Beginning as early as 2010 a network of tunnels will be dug and simultaneously loaded with the most radioactive waste from the 100 or so nuclear reactors that supply about 20 percent of the nation's electricity.

Building a massive mine to store nuclear waste wasn't in anyone's original game plan. At the dawn of the nuclear age engineers saw the "spent fuel" that came out of reactors as potentially more valuable than the slightly enriched uranium dioxide "fresh fuel" that went in. Nuclear fission does more than make the steam that spins electric generators. A portion of the uranium fuel undergoes a transformation, yielding a cornucopia of radioactive elements. The most troubling of these is plutonium-239, which can be chemically separated and then used to make fuel for other types of power reactors and nuclear bombs.

As the concentration of these newly created elements increases in the fuel, the thermal efficiency of the reactor decreases. Every two to three years a typical 1000-megawatt reactor must be shut down and a third of its 100-metric-ton fuel load replaced. Fresh out of the reactor, "spent fuel" is so dangerous it must be stored underwater. According to the original plan, Uncle Sam was then supposed to back a radiation-shielded truck up to the plant and cart away the waste to a reprocessing site, where the useful elements would be removed and recycled.

Although technically achievable, reprocessing plants became intolerably expensive to operate. A new federal strategy evolved. Uncle Sam would still take the spent fuel, but now it would be put in a deep hole in the middle of nowhere, watched for a century or so and, if no one wanted it back, abandoned. The Department of Energy (DOE), which is responsible for nuclear waste, likes to call these steps "emplacement," "monitoring" and "closure." By the time the job is done in 2071, these tasks could have cost as much as $50 billion.

Obviously, no one wants this sort of hole in their backyard. After considerable political wrangling, choices for a "permanent high-level civilian waste repository" narrowed to what seemed to be the perfect location, beneath Yucca Mountain, next door to the country's above-ground nuclear weapons testing site.

If constructed, the repository (see accompanying illustrations) will hold nearly 3 billion curies of radiation. By comparison, the accident at Three Mile Island released 15 curies, mostly as short-lived radioactive iodine. A substantial portion of the radiation contained inside Yucca Mountain will be emitted from plutonium, which has a half-life of more than 20,000 years.

Bottling The Genie
How do you contain so deadly a genie for so long a time? As POPULAR MECHANICS saw during a recent trip to Yucca Mountain, DOE's strategy can be summed up in one word--carefully.

"Our estimate is that the first packages will fail in 10,000 years," Daniel R. Wilkins, assistant general manager of the repository, tells PM. "After that we're relying on the mountain to contain the waste." The "packages" are casks made of steel and a highly corrosion-resistant inner lining. Each will hold 21 or 44 "reactor fuel assemblies." Some assemblies contain enough plutonium to build a bomb. However, because the plutonium is diffused inside the fuel pellets within the assemblies, no one believes there is any credible risk of an explosion. Concerns center on more subtle dangers, principally the presence of water.

Water is one thing that there doesn't appear to be much of atop Yucca Mountain. The rugged, 1000-ft.-tall flat-top mountain overlooks the Amargosa Desert. Running north to south for about six miles, it is made of layers of volcanic tuff--broken or fragmented rock created when a volcano explodes--that was laid down between 11.5 million and 15 million years ago. After being packed in casks at a yet-to-be-constructed processing area on the surface, the wastes will be deposited into tunnels or "drifts" dug into a formation of welded tuff between about 600 ft. and 900 ft. thick. The drifts will be cut with a boring machine the size of several train engines.

Thus far, construction crews have cut a 5-mile, 25-ft.-dia. exploration tunnel, a pair of ramps to the surface and several side alcoves. DOE scientists are hopeful that experiments now being conducted in these alcoves will generate sufficient scientific data about the geologic, mechanical and chemical conditions inside the rock to convince the Nuclear Regulatory Commission (NRC) to issue a construction permit to dig the actual burial tunnels and an operating license that will allow them to accept nuclear wastes, which are now stored at power plants.

Yucca Mountain's principal opponent, the state of Nevada, says the data produced thus far is quite sufficient to show just the opposite. It claims the mountain leaks.

The Heat Is On
"Originally we thought there would be very slow [water] infiltration," says Wilkins. "New evidence suggests there are some fractures that will allow flows from the surface to the repository and from the repository down." The water table is about 900 ft. below the waste emplacement tunnels, and the terrain is geologically stable. For these reasons most agree it is unlikely the water table could rise high enough to reach the casks. Despite the newly discovered fractures, water trickling down from the top of the mountain doesn't seem to cause much concern, either. However, water evaporating from the rock into the tunnels is another matter.

The apparently solid-looking welded tuff in which the repository will be dug is actually riddled with microscopic pores and fracture spaces, says Steven Frishman, a geologist and the technical policy coordinator for the State of Nevada Nuclear Waste Project Office. He believes that surface water moving through the fractures has become trapped in about 80% of the pore space in the rock.

DOE scientists dismiss the importance of the water. They say that heat emitted by the casks will elevate the temperature of the rock surfaces surrounding the drifts sufficiently high to drive away moisture, thus keeping the casks dry and corrosion-free for thousands of years. One of the ways they intend to prove this point is with a series of progressively larger and larger rock-heating experiments.

On The Scene
PM's 17-minute tram ride 800 ft. below Yucca Mountain ends not far from Alcove 5, the site of the largest of these experiments, the Drift-Scale Test. It is taking place inside a 156-ft. section of welded tuff that has been sealed from the adjoining tunnel. Beyond an insulating barrier, heaters are slowly warming 13,000 cubic yards of surrounding rock to a temperature well above the boiling point, using electric heaters. A nearby digital display shows that the heaters have been running for 3000 hours. The test will take about four years to complete. About halfway through, the power will be turned off and the rock will begin cooling to ambient temperatures.

From the thermal, mechanical, hydrological and chemical data DOE collects, it hopes to refine computer models that predict the long-term effects of heat generation, explains DOE geophysicist Robert Yasek. "The Drift-Scale Test will be the largest test of its type done thus far in the world," he says. It will be one of the key sources of data that the NRC examines when it decides whether to grant the operating license the repository would need before it could accept waste.

Getting Wet
Nevada's Frishman says the NRC doesn't need to wait four years. The data collected thus far, he says, has already revealed a critical, overlooked flaw in the repository's basic design. Consulting notes from his visit to the test site, Frishman explains: "The air temperature inside the sealed alcove was 262° F and the rock was 252° F. Yet, the relative humidity was 11 percent. It should be virtually zero."

The presence of humidity, says Frishman, is proof positive that as the heat pushes moisture away from the surface of the tunnel walls, but it is also drawing moist air in from water-filled pores in the mountain. He goes on to explain that as long as the tunnel walls remain at temperatures above the boiling point, this isn't necessarily a problem. The difficulty, he says, will come hundreds of years in the future, after the mine has been sealed but while its contents are still lethally radioactive. At this point, Frishman foresees the humidity in the tunnels rising to nearly 100 percent.

Frishman believes the unanticipated humidity will accelerate deterioration of the casks and ultimately cause them all to fail, spilling their radioactive contents.

DOE insists that none of the problems it has encountered thus far are project killers. However, in a meeting with an independent presidential advisory panel on Yucca Mountain, it has begun to paint a gloomier picture. Among the items presented by DOE was a graphic showing how leakage of radioactive material would enter the ground water below the repository, and then work its way back to the surface, directly exposing humans, food and water supplies to radiation (see diagram above).

"It's not just some local farmers who will be exposed to this radiation," says Frishman. "There are about 2500 acres of alfalfa planted in the basin. It is used as feed for cows that produce 32,000 gal. of milk every day. And, it's all shipped to Los Angeles." Suddenly, a deep hole in the middle of nowhere seems a lot closer to home.

Source: http://www.popularmechanics.com/science/research/1281721.html?page=1&c=y
 

Munkey

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#2
There are some great illustrations on the website, well worth checking out.

Also you may want to put the kettle on as the article is quite long but very interesting.

Does anyone know what us Brits do with our nuclear waste? Do we spend the extra money to make it safer?
 

little_pob

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#3
Other countries ship some of their waste to us for refining, so I assume we reprocess it. IIRC its all done at Sellafield (formerly Windscale).
 

Munkey

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Wow I wasn't aware that we imported countries nuclear waste for refinement.

At least we're spending the money to make the nuclear waste clean rather than just a big hole and dump it all in, the US which is richer really should be following our lead.
 

stevemac40

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I don't know this for 100% sure but was told it by an Operator at Nuclear plant that.

Our power stations were built ontop of very large concrete lined pits, when spent, the uranium rods are dropped into the pits below. The real problem comes in the decomissioning of the plant as they are sat on som much nuclear waste. Like I said, I haven't researched this but thats what i've been told.
 

nozzer

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Other countries ship some of their waste to us for refining, so I assume we reprocess it. IIRC its all done at Sellafield (formerly Windscale).
There's also quite a bit of work done at the SpringFields site near Preston in Lancashire. This site was the first site in the world to produce nuclear fuel for a commercial reactor (mid 1940's). It did handle a lot of the Magnox fuel element assembly and reprocessing as well as handling large amounts of Uranium Oxide and Hexafloride processing.

The site also housed one of the UK atomic energy authorities research centres complete with a small reactor similar to the one used for testing by the US for the manhattan project. There's a lot of secrecy surrounding this particular establishment but its believed much of the UK's stock of plutonium was manufactured there.

The site is now slowly being decommisioned (I think most of the Magnox work has now ceased and the UKAEA site has gone)) but still handles quite a lot of the newer fuel type fabrication and re-processing.
 

digidude

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itll cost $50 billion to bury some stuff thats going to end up causing a disaster?

surely itd be cheaper, safer and better for the future to put the crap in very hard, i mean really really hard, in case of a cock up, boxes, put it on rockets, and fire it at the sun

if they do it at night itss be even less dangerous :proud:
 

witchy

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make this hauntingly beautiful patch of desert
Isn't that spin-talk for "desolate waste land" ? :)

surely itd be cheaper, safer and better for the future to put the crap in very hard, i mean really really hard, in case of a cock up, boxes, put it on rockets, and fire it at the sun
Don't do that mate, you might blow the sun out! ;)
 

gez

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Wow I wasn't aware that we imported countries nuclear waste for refinement.

At least we're spending the money to make the nuclear waste clean rather than just a big hole and dump it all in, the US which is richer really should be following our lead.
there has recently been talk of burying in this country as well but as usual its a case of "not in my backyard go somewhere else"
 

Munkey

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there has recently been talk of burying in this country as well but as usual its a case of "not in my backyard go somewhere else"
Thank god we're a small island then, if we had the land mass of the US I'm certain we'd be burying the nuclear waste two.

The strange thing when reading that article is that work has already begun, yet according to Frishman there is a danger of moisture levels reaching 100% at some stage which would cause the radiation to leak.

I also found the stats on the levels of radiation we are exposed to in cities very interesting. Is radiation found in nature anywhere, I'm curious? (aside from uranium)
 

nozzer

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I also found the stats on the levels of radiation we are exposed to in cities very interesting. Is radiation found in nature anywhere, I'm curious? (aside from uranium)
Yes, we are exposed to radiation from natural sources including "The sun" (cosmic rays) and various element isotopes (eg carbon, potassium, thorium, radium, radon, uranium).

Its not that many years ago that luminous clocks and watches had a dab of radium on the pointers to give the glow !

The most common natural radioactive health hazard is arguably radon gas. This is said to be the highest cause of lung cancer after smoking. Radon gas can be found in most places but often has significantly higher concentrations in areas where the base rock is granite.

Plutonium is a man made element that does not occur naturally (at least on this planet).
 
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#15
Oppenheimer wondered whether the first A-bomb test would set the atmosphere on fire.

I love that idea, that a man of such genius had so many doubts about foraging into the unknown.

Not sure what it has to do with this thread; I just remembered.

Nuclear power is the option if anthropogenic global warming and its consequences are true. The green lobby won't allow it though.
 

Munkey

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Yes, we are exposed to radiation from natural sources including "The sun" (cosmic rays) and various element isotopes (eg carbon, potassium, thorium, radium, radon, uranium).

Its not that many years ago that luminous clocks and watches had a dab of radium on the pointers to give the glow !

The most common natural radioactive health hazard is arguably radon gas. This is said to be the highest cause of lung cancer after smoking. Radon gas can be found in most places but often has significantly higher concentrations in areas where the base rock is granite.

Plutonium is a man made element that does not occur naturally (at least on this planet).
Thanks for that explanation.

I am curious though. Does anyone know why small towns and villages have very little or no radiation exposure compared to big cities if both are not exposed to the elements that you have listed?
 

little_pob

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Its literally because there is more in a city than rural areas.

Concrete is made from several substances that can contain radioisotopes, e.g. silicone in the sand aggregate has a number of radioisotopes: http://en.wikipedia.org/wiki/Isotopes_of_silicon

Also natural radioisotopes of carbon occuring in hydrocarbon fuels, more fuel is burnt in cities, therefore you'd expect a higher level of 14C (http://en.wikipedia.org/wiki/Carbon-14).

I assume that like heat being trapped by buildings, the higher building density of urban areas will cause the radioisotopes to dissipate more slowly as they bounce off buildings.
There's also quite a bit of work done at the SpringFields site near Preston in Lancashire. This site was the first site in the world to produce nuclear fuel for a commercial reactor (mid 1940's). It did handle a lot of the Magnox fuel element assembly and reprocessing as well as handling large amounts of Uranium Oxide and Hexafloride processing.

The site also housed one of the UK atomic energy authorities research centres complete with a small reactor similar to the one used for testing by the US for the manhattan project. There's a lot of secrecy surrounding this particular establishment but its believed much of the UK's stock of plutonium was manufactured there.

The site is now slowly being decommisioned (I think most of the Magnox work has now ceased and the UKAEA site has gone)) but still handles quite a lot of the newer fuel type fabrication and re-processing.
Now that I didn't know. Which is worrying as its closer to where I live than Sellafield!
 
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Munkey

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Its literally because there is more in a city than rural areas.

Concrete is made from several substances that can contain radioisotopes, e.g. silicone in the sand aggregate has a number of radioisotopes: http://en.wikipedia.org/wiki/Isotopes_of_silicon

Also natural radioisotopes of carbon occuring in hydrocarbon fuels, more fuel is burnt in cities, therefore you'd expect a higher level of 14C (http://en.wikipedia.org/wiki/Carbon-14).

I assume that like heat being trapped by buildings, the higher building density of urban areas will cause the radioisotopes to dissipate more slowly as they bounce off buildings.


Now that I didn't know. Which is worrying as its closer to where I live than Sellafield!
Thanks for posting those links. Some interesting reading for me.